In the case where a control device for an AC rotating machine is used for, for example, electrical power steering, even when a failure occurs in a specific portion, the AC rotating machine is desired to be continuously driven while avoiding the failure.
For example, a related-art control device for an AC rotating machine described in Patent Literature 1 includes current control portion for determining phase voltage commands in accordance with a torque current command and currents respectively flowing in phases of an electric motor, a switching element driving circuit for instructing an inverter to perform a switching operation based on the respective phase voltage commands, the inverter for driving the electric motor in response to a switching operation signal, current detectors arranged in series with respect to switching elements of the respective phases of the inverter, and short-circuit portion specifying portion for storing a test pattern indicating a predetermined combination for turning ON the switching elements of the inverter and for specifying a portion at which a short-circuit failure occurs, based on the test pattern and current detection values of the respective phases, which are detected by the current detectors as responses to the test pattern. As a result, the portion at which the short-circuit failure occurs can be quickly and precisely specified.
By providing two sets of windings to the AC rotating machine, the AC rotating machine can be continuously driven while avoiding a failure. For example, a related-art control device for an AC rotating machine described in Patent Literature 2 has a configuration in which, two sets of windings and two sets of inverters for controlling currents flowing through the two sets of windings are provided to the AC rotating machine so that the currents can be individually controlled. In case of a failure in one of the windings or one of the inverters, all the switching elements of a failure system are turned OFF to reduce or cancel a brake torque. Moreover, it is also described that the drive is continued for the non-faulty phases of the failure system so as to reduce or cancel the brake torque in a non-faulty system.